INTRODUCTION — Diabetes mellitus is a chronic condition that can lead to complications over time. These complications include: Coronary heart disease, which can lead to a heart attack Cerebrovascular disease, which can lead to stroke Retinopathy (disease of the eye), which can lead to blindness Nephropathy (disease of the kidney), which can lead to kidney failure and the need for dialysis Neuropathy (disease of the nerves), which can lead to, among other things, ulceration of the foot requiring amputation
Many of these complications produce no symptoms in the early stages, and most can be prevented or minimized with a combination of regular medical care and blood glucose monitoring.
CONTROLLING BLOOD SUGAR — The long-term complications of diabetes result from the effects of hyperglycemia (elevated blood glucose levels) on blood vessels. Two important studies, the Diabetes Control and Complications Trial (DCCT) in patients with type 1 diabetes and the United Kingdom Prospective Diabetes Study (UKPDS) in patients with type 2 diabetes, found that patients with lower blood glucose values had fewer complications than those with higher values.
Thus, keeping blood sugars close to normal can help prevent the long-term complications of diabetes mellitus. However, there are some risks associated with tight control, particularly an increased risk of hypoglycemia (low blood sugar).
Monitoring blood sugar levels — Monitoring blood sugars with finger sticks at home can indicate how well diabetes is controlled and serves as a guide to adjusting therapy. (See "Patient information: Self-blood glucose monitoring"). For most patients, a target for fasting blood glucose and for blood glucose levels before each meal is 80-120 mg/dl (4.4 to 6.6 mmol/L); however, these targets may need to be individualized for a patient by their doctor or health care team.
A blood test called A1C is also used to monitor blood sugar control; the result provides an average of blood glucose levels during the previous one to three months. An A1C of 7 percent or less is recommended; this corresponds to an average blood glucose of 150 mg/dL (8.3 mmol/L, show figure 1). The target may be somewhat higher in people who are older or who have other conditions that increase the risks associated with hypoglycemia. Patients who are unable to reach this goal can be reassured that even small decreases in A1C lowers the risk of diabetes-related complications to some degree.
The combination of A1C and fingerstick blood sugars provides information about the average blood sugar as well as daily fluctuations in blood sugar.
Type 1 diabetes — Blood sugar control in type 1 diabetes requires some form of insulin, which can be given with insulin injections, an insulin pump, or a combination of inhaled insulin and insulin injections. Most healthcare providers recommend intensive insulin therapy, which requires frequent injections, inhaled insulin, or use of an insulin pump and blood glucose monitoring. (See "Patient information: Diabetes type 1: Insulin treatment").
Intensive insulin therapy increases the risk of low blood glucose, is more expensive than traditional insulin therapy, and requires that patients monitor their blood glucose levels, dietary intake and activities; the severity of diabetic complications or hypoglycemia may limit this form of therapy in some patients with type 1 diabetes. Patients can experience weight gain with intensive insulin therapy; regular exercise and monitoring dietary intake can prevent weight gain. (See "Patient information: Hypoglycemia (low blood glucose) in diabetes").
Type 2 diabetes — Blood glucose control in type 2 diabetes may be possible with lifestyle changes alone or in combination with oral medications. Insulin is necessary in some cases in early treatment; many patients who do not initially require insulin may do so over time as their ability to manufacture insulin decreases. Generally the insulin regimen for type 2 requires fewer injections and less intensive monitoring than for type 1, although intensive insulin therapy may be recommended for some patients (See "Patient information: Diabetes type 2: Insulin treatment").
EYE COMPLICATIONS — Regular eye examinations are essential for detecting eye complications (called retinopathy) at an early stage, when they can be monitored and treated to preserve vision. This examination should be performed by a doctor who specializes in the eyes (called an ophthalmologist or optometrist). An eye exam should include dilating the pupils (with medicated eye drops) in order to completely visualize the retina. Unless the pupils are medicated, they contract in response to light, making it impossible to view the entire retina.
In some patients with retinopathy, photographs of the retina will be taken to monitor and better visualize the changes. The risk of diabetic retinopathy varies with the type and duration of diabetes and with other life events. Thus, the screening guidelines differ from one person to another.
Type 1 diabetes — People with type 1 diabetes should have an eye examination by an ophthalmologist or optometrist beginning five years after they are diagnosed with diabetes, although screening is usually not necessary before puberty. Patients who have difficulty with their vision or who require glasses or contacts may need to be seen sooner. The frequency of subsequent examinations will depend upon the results of the initial exam. Doctors usually recommend eye exams every one to two years after the initial examination.
Type 2 diabetes — People with type 2 diabetes should have an eye examination by an ophthalmologist or optometrist when they are first diagnosed with diabetes. The frequency of subsequent exams will depend upon the results of the initial examination. Doctors usually recommend eye exams every one to two years after the initial examination.
FOOT CARE — Diabetes can decrease the blood supply to the foot and damage the nerves that carry sensation. These changes put the feet at risk for potentially serious complications such as foot ulcers. Foot complications are very common among people with diabetes, and may be unnoticed until the condition is severe. (See "Patient information: Foot care in diabetes").
Self exam — Patients with diabetes should examine their feet for changes every day. It is important to examine all parts of the feet, especially the area between the toes. Patients should look for broken skin, ulcers, blisters, areas of increased warmth or redness, or changes in callus formation; a healthcare provider should be notified if any of these changes are found.
Patients should include a self-examination in their daily bathing or dressing routine. It may be necessary to use a mirror to see the bottoms of the feet clearly. Patients who are unable to reach their feet or see them completely, even with the help of a mirror, should have someone else (such as a spouse or other family member) assist with the examination.
Clinical exam — During a routine medical visit, the clinician will check the blood flow and sensation in the feet. In people with type 1 diabetes, annual foot examinations should begin five years after diagnosis. In people with type 2 diabetes, annual foot exams should begin at the time of diagnosis.
During a foot examination, the clinician will look for changes such as ulcers, cold feet, thin skin, bluish skin color, and skin breaks associated with athlete's foot. The clinician will also test the sensation in the feet to determine if it is normal or diminished. Patients with decreased sensation are at risk for foot injuries that are unnoticed due to lack of pain.
KIDNEY COMPLICATIONS — Diabetes can alter the normal function of the kidneys. A urine test which measures the amount of protein (albumin) in the urine can alert a healthcare provider that diabetes is affecting the kidney's filtering action. Microscopic amounts of albumin in the urine (microalbuminuria) can be an early indicator of diabetes-related kidney complications (called nephropathy). The amount of albumin in the urine can also help the provider determine if nephropathy is worsening. (See "Patient information: Protein in the urine (proteinuria)").
Urine screening tests should begin in people with type 1 diabetes about five years after diagnosis, and in people with type 2 diabetes at the time of diagnosis. If the test shows that there is protein in the urine, tight blood glucose and lipid control are recommended; a medication may be recommended if albuminuria does not improve.
A blood pressure medication (an ACE inhibitor or angiotension receptor blocker [ARB]) is generally recommended for patients with albuminuria that does not improve, even if blood pressures are normal. Patients with elevated blood pressures and albuminuria are also treated with an ACE inhibitor or ARB. These medications decrease the amount of protein in the urine and can prevent or slow the progression of diabetes-related kidney disease.
HYPERTENSION AND RELATED COMPLICATIONS — Many people with diabetes have hypertension (high blood pressure). Although high blood pressure produces few symptoms, it has two negative effects: it stresses the cardiovascular system and increases the progression of diabetic complications of the kidney and eye. A healthcare provider can diagnose high blood pressure by measuring blood pressure on a regular basis. (See "Patient information: High blood pressure overview").
A blood pressure reading below 130/80 is an ideal goal for most people with diabetes who do not have kidney complications; a lower blood pressure goal (<120/75) may be recommended for people with diabetes who have kidney complications.
If a patient is diagnosed with prehypertension (>120/80), the healthcare provider may recommend weight loss, exercise, decreasing the amount of salt in the diet, quitting smoking, and decreasing alcohol intake. These measures can sometimes reduce blood pressure to normal. (See "Patient information: High blood pressure, diet and weight").
If these measures are not effective or the blood pressure must be lowered quickly, the provider will likely recommend one of several high blood pressure medications. The provider can discuss the pros and cons of each medication and the goals of treatment (See "Patient information: High blood pressure treatment").
HEART COMPLICATIONS — In addition to lowering blood glucose levels, a number of other measures are important to reduce the risk of cardiac disease. Quit smoking Manage high blood pressure with lifestyle modifications and/or medication(s) Patients should have a fasting lipid blood test to measure cholesterol and triglycerides, and modify their diets. some patients may need medication to lower their LDL ("bad cholesterol") or trigylcerides, if they are high.
If medication is needed, a statin drug should be included whenever possible. The statin drugs have been shown to decrease the future risk of heart attacks, strokes, and death in people with diabetes who are over age 40, even when cholesterol levels are normal. The American Diabetes Association recommends that patients with diabetes have a low density lipoprotein (LDL) cholesterol level less than 100 mg/dL. Some studies suggest lowering LDL to 70 to 80 mg/dL. (See "Patient information: High cholesterol and lipids (hyperlipidemia)"). Aspirin (81 to 162 mg per day) is recommended for all persons with diabetes over the age of 40 years. (See "Patient information: Aspirin and heart disease").
PREGNANCY AND DIABETES — Control of diabetes and its potential complications is especially important in women planning to become pregnant, as well as in those who already are pregnant. Controlling blood glucose levels before and during pregnancy decreases the risk of a number of complications in both the mother and the baby. A separate topic review is available on this subject. (See "Patient information: Care during pregnancy for women with type 1 or 2 diabetes").
Pregnancy can cause a worsening of diabetic retinopathy. Thus, women with type 1 or 2 diabetes who become pregnant should have an eye examination by an ophthalmologist or optometrist during the first trimester (three months) of their pregnancy. The frequency of subsequent eye exams during pregnancy will depend upon the results of the initial examination. In most cases, doctors recommend eye exams every three months until delivery.
These guidelines do not apply to women who have gestational diabetes -- a form of diabetes that develops during pregnancy and usually resolves after delivery. These women are not at risk for diabetic retinopathy.
THE IMPORTANCE OF REGULAR MEDICAL CARE — Regular medical care is critical to long-term health for people with diabetes, particularly when it comes to preventing, detecting, and slowing the progression of complications. A healthcare provider can recommend a regular schedule for visits, screening, and monitoring tests based upon a patient's type of diabetes (1 or 2), the duration of the disease, the presence of any complications, and the presence of other underlying medical problems.
In addition to diabetes care, patients also need to be sure they have regular screening for other health problems. For women, this may includes a cervical cancer screening, mammogram and clinical breast exam, and bone density testing. For men, prostate cancer screening is recommended after age 40. For both men and women, colon cancer screening is recommended after age 50. (See "Patient information: Screening for cervical cancer" and see "Patient information: Screening for breast cancer" and see "Patient information: Osteoporosis causes; diagnosis; and screening"). and see "Patient information: Prostate cancer screening" and see "Patient information: Screening for colon cancer").
WHERE TO GET MORE INFORMATION — Your healthcare provider is the best source of information for questions and concerns related to your medical problem. Because no two patients are exactly alike and recommendations can vary from one person to another, it is important to seek guidance from a provider who is familiar with your individual situation.
This discussion will be updated as needed every four months on our web site (www.patients.uptodate.com). Additional topics as well as selected discussions written for healthcare professionals are also available for those who would like more detailed information.
A number of web sites have information about medical problems and treatments, although it can be difficult to know which sites are reputable. Information provided by the National Institutes of Health, national medical societies and some other well-established organizations are often reliable sources of information, although the frequency with which they are updated is variable. National Library of Medicine
(www.nlm.nih.gov/medlineplus/healthtopics.html)
National Institute of Diabetes and Digestive and Kidney Diseases
(www.niddk.nih.gov/)
American Diabetes Association (ADA)
(800)-DIABETES (800-342-2383)
(www.diabetes.org)
The Hormone Foundation
(www.hormone.org/public/diabetes.cfm, available in English and Spanish)
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2. Effect of intensive diabetes management on macrovascular events and risk factors in the Diabetes Control and Complications Trial. Am J Cardiol 1995; 75:894.
3. Abraira, C, Colwell, JA, Nuttall, FQ, et al. Veterans Affairs Cooperative Study on Glycemic Control and Complications in Type II Diabetes (VACSDM): Results of a feasibility trial. Diabetes Care 1995; 18:1113.
4. Nathan, DM, Cleary, PA, Backlund, JY, et al. Intensive diabetes treatment and cardiovascular disease in patients with type 1 diabetes. N Engl J Med 2005; 353:2643.
5. Sustained effect of intensive treatment of type 1 diabetes mellitus on development and progression of diabetic nephropathy: the Epidemiology of Diabetes Interventions and Complications (EDIC) study. JAMA 2003; 290:2159.
6. Gray, A, Raikou, M, McGuire, A, et al. Cost effectiveness of an intensive blood glucose control policy in patients with type 2 diabetes: economic analysis alongside randomised controlled trial (UKPDS 41). United Kingdom Prospective Diabetes Study Group. BMJ 2000; 320:1373
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